The invention relates to ducts for routing engine cooling air to pneumatically blast dust, chaff and other debris off the top of an axial separator and associated drive mechanism.
In threshing a harvested crop, the grain is separated from straw and chaff and deposited into a holding tank. With conventional combines the harvested crop is directed to a transversely mounted threshing cylinder and concave, which threshes the crop, separating the grain from straw. The residue is then directed to a beater further separating the grain from straw. The straw residue is then passed over oscillating apertured straw walkers which direct the straw out of the back of the combine while allowing additional grain to fall through the apertures. Grain and chaff falling from the threshing concave and straw walkers is directed to a cleaning shoe for separating the chaff from the grain. A blower assembly is used in this final step to blow the lighter chaff away from the heavier grain.
In an axial flow combine, the grain is directed to a cylindrical tube housing a rotor. The harvested crop is threshed and separated in the cylindrical tube with the grain and chaff falling therefrom in a manner similar to the conventional combine. Case International of Racine, Wis. currently markets and manufactures such a combine having a single rotor. Ford New Holland of New Holland, Pa. currently markets and manufactures this type of combine having a pair of rotors mounted side-by-side.
A hybrid machine having a transverse threshing cylinder and a pair of axial separating units is disclosed in U.S. Pat. No. 4,739,773, which is incorporated herein by reference. The axial separating units comprise cylindrical tubes having rotors housed therein. It has been found that dust, chaff and other debris collects on the top of the axial separating units.
It is known to provide an air duct that receives an air stream from a cooling system fan to blow debris off the top portion of an axial separator unit. Such ducts tend to block or hinder air from flowing through the cooling system and fan. It would be desirable to provide such a duct that minimizes or reduces the blockage of air flowing through the cooling system such that the cooling system can operate more effectively. Such ducts are typically positioned proximate the engine and therefore can obstruct an operator""s access to the engine during maintenance procedures. It would be desirable to provide such a duct that is relatively small so that the obstruction to the engine is reduced. These ducts are designed to blow debris off the top of axial separator units, and therefore it would also be desirable for such a duct to provide an air stream with sufficient volume and velocity to effectively blow debris from that area.
The present invention is directed to using engine cooling air to pneumatically blast dust, chaff and other debris off the top of the axial separator units and the linkage that drives the rotors of the axial separator units. Duct work directs cooling air from the engine cooling system to the top of the axial separator and the rotor drive linkage. A deflector located above the separator divides the air into a forward component and a rearward component.
The duct work includes an arcuate conduit having an inlet proximate the engine cooling fan for receiving therefrom a generally horizontally travelling air stream. The conduit extends in an arc that gradually redirects this air stream generally vertically downwardly through the floor of a work platform and onto the top of the axial separator. As the air stream exits the conduit it strikes a flow divider that redirects the air into generally horizontal forward and rearwardly directed components. These air streams help clear debris off the top of the axial separator units and the drive linkage that drives the rotors of the axial separator units. The duct includes a neck portion that has a relatively small cross sectional area through which the air stream passes. This neck portion serves as a restriction that generally prevents the air stream from swirling upwardly in that location. Flow through the duct is thereby enhanced. The outlet of the duct flares outwardly from the neck portion to define a larger or expanded cross sectional area through which the air flow can pass, thereby further enhancing flow through the conduit.